pg_constraint
#The catalog pg_constraint
stores check, primary key, unique, foreign key, and exclusion constraints on tables, as well as not-null constraints on domains. (Column constraints are not treated specially. Every column constraint is equivalent to some table constraint.) Not-null constraints on relations are represented in the pg_attribute
catalog, not here.
User-defined constraint triggers (created with CREATE CONSTRAINT TRIGGER
) also give rise to an entry in this table.
Check constraints on domains are stored here, too.
Table 51.13. pg_constraint
Columns
Column Type Description |
---|
Row identifier |
Constraint name (not necessarily unique!) |
The OID of the namespace that contains this constraint |
|
Is the constraint deferrable? |
Is the constraint deferred by default? |
Has the constraint been validated? Currently, can be false only for foreign keys and CHECK constraints |
The table this constraint is on; zero if not a table constraint |
The domain this constraint is on; zero if not a domain constraint |
The index supporting this constraint, if it's a unique, primary key, foreign key, or exclusion constraint; else zero |
The corresponding constraint of the parent partitioned table, if this is a constraint on a partition; else zero |
If a foreign key, the referenced table; else zero |
Foreign key update action code: |
Foreign key deletion action code: |
Foreign key match type: |
This constraint is defined locally for the relation. Note that a constraint can be locally defined and inherited simultaneously. |
The number of direct inheritance ancestors this constraint has. A constraint with a nonzero number of ancestors cannot be dropped nor renamed. |
This constraint is defined locally for the relation. It is a non-inheritable constraint. |
If a table constraint (including foreign keys, but not constraint triggers), list of the constrained columns |
If a foreign key, list of the referenced columns |
If a foreign key, list of the equality operators for PK = FK comparisons |
If a foreign key, list of the equality operators for PK = PK comparisons |
If a foreign key, list of the equality operators for FK = FK comparisons |
|